Hmmm....reviews say it is a sensitive receiver, almost too sensitive. So 25-30ft of wire outside as high as possible fed with RG58 coax to the SO239 on the back. Indoor antennas used to be decent performers, but with modern electronics, sure is a lot of RFI about! Trust me, I know!
You can use WWV at 10mhz for testing the effectiveness of whatever antenna you choose.
HAVE FUN...